(maybe) it's the end of the male as we know it

Article: The End of 'Man'

The segment of human genes that defines maleness—the Y chromosome—is so meager that some scientists predict it will evolve out of existence in 125,000 years. The ninety genes that determine who is born a boy are so vulnerable, some scientists say, that they deserve labels like DNA "graveyard" or "Adam's curse."

No one has yet predicted the end of the male species, although it could theoretically happen. Males generally carry one Y chromosome, with its few genes, and one X, which has more than a thousand. The Y, lacking a matched genetic partner, exchanges little genetic material with the X. Women, on the other hand, have two X chromosomes that exchange vastly more genes.

Since the Y lacks this high rate of recombination, the scientific mystery has been how the "male" genetic code survives generation after generation. Scientists wonder why maleness, with its lack of genetic resources, has not simply withered away.

The answer, according to new research, may be that the Y has found a way to keep replenishing itself.

During fertilization, when the mother and father exchange their unique genetic blueprints, the mother and father's DNA exchange places with each other at random points. This "crossing over," or mixing, of genetic material is believed to ensure the health of the human genome by adding diversity it its genes. The process weeds out the weak genes and perpetuates the strong ones.

This crossing over is extensive between two X chromosomes. But the Y chromosome lacks a full partner and is denied full genetic "sex," or recombination. The Y only exchanges genetic material at its ends, where it matches the X chromosome. All the other genes on the Y apparently receive no upgrading and repair by the swapping of genetic material.

Nevertheless, genetic "man" has survived for 300 million years, but scientists disagree on how much longer he can last.

That story begins with the apparent history of the X and Y chromosomes. They are believed to have been identical in mammals 300 million years ago. After a major mutation occurred, a male-determining gene appeared on the Y chromosome. The gene is now called the SRY gene for "Sex-determining Region of the Y." This mutation had historical significance because it marked the birth of "sex" and the distinctive journeys of the Y and the X.

Although the Y chromosome has few genes, they are very active in producing sperm for reproduction. But because of this activity, and because they are switched "on" so often, the Y genes are particularly susceptible to mutation.

The Oxford geneticist Brian Sykes, who describes the Y chromosome as a "graveyard of rotting genes," calculates that this high mutation rate will destroy the fertility of the Y in 125,000 years. That means that the Y chromosome will no longer have the genetic power to make males, and the natural reproduction of "man" will end.

Other scientists give the Y a better chance. Biologists Jennifer Graves of the Australian National University calculates that the Y chromosome, and thus males, will last perhaps 14 million more years. Her estimate is based on a more gradual gene decay.

A new theory, however, not only rejects such pessimism, but tries to explain why the weakling Y chromosome has lasted so long. In 2003, David Page, head of the Whitehead Institute and a professor at the Massachusetts Institute of Technology (MIT), presented his discovery that a major part of the Y chromosome self-corrects its mutations. He studied the region of genes that produced the most sperm and found eight extra gene sequences—mirror images of the genes called palindromes—that allow the Y to recombine with itself.

A genetic palindrome is a DNA sequence with letters that read the same in either direction (such as the word "tenet" or phrase "Madam, in Eden I'm Adam"). Page argues that the Y chromosome makes a hairpin loop (see diagram) to recombine its genes, keeping them healthy after millions of years of genetic reproduction. This process of "gene conversion," Page says, can occur up to six hundred times per pairing.

He and his colleagues compared the DNA in the Y chromosome of chimpanzees and humans and found that even the genes that do not participate in palindrome conversion change very little over six million years—the point at which chimp and human lines diverged. Although the Y has lost genes, Page says, it has also gained them and become very specialized and efficient.

Graves, the Australian geneticist, is not convinced. She doubts that the palindrome effect really recombines genes,and says it may further erode them. Sykes adds in his book, Adam's Curse, "The Y chromosome is just as lonely as ever—though we now know that it talks to itself as it spirals towards oblivion."

But even if this means the end of natural male reproduction, Graves says, other genes might mutate and take over the SRY's role. A new species of humans might result. The Y has disappeared from two rodent species, for example, but males are still being born. At MIT, Page puts his money on the Y as we know it. He sees it not as a graveyard but as a lean, efficient reproduction machine—here to stay.

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Now this is a slightly bizarre article. I never thought I'd read about the possibility of the extinction of the male human species. I mean, really. Who'da thunk?

What's amusing is how the article notes that the genes that ultimately determine a boy are "vulnerable" - that's the last word I'd use to describe males as a whole, considering the largely male-dominated society we live in. Yes, gender equality has come a long way, but I think it still has a ways to go.

The reason why I feel compelled to include this article in my journal is because I don't think this sits well with a Judaeo-Christian belief of God and the creation of humans. Surely God wouldn't have created Adam and Eve in such a way that the male species would eventually die out before the female race (which incidentally is the total opposite of the movie Children of Men, where there is only one female left on Earth and she is pregnant and it's so-and-so's duty to protect her from everybody else who is trying to kill her, etc). Especially considering that it was Eve who supposedly sinned by eating from the Tree of Knowledge. Nor would He, in my opinion, create humans in such a way that we would evolve into a new method of breeding.

Admittedly, the end of the article notes that perhaps a new species of human will be born from the disappearance or deterioration of the Y chromosome.. thus ending 'natural male reproduction' as mentioned in the article, and creating a new form of human reproduction which would, in time, become 'natural' reproduction.

Genetic mutation - the phrase sounds like such an unnatural activity, but I'm sure it happens all the time. It's like the concept of 'normal'. There can hardly be such a thing as normal in my opinion; one is merely making a huge generalisation over the population when describing something as having normal or usual attributes.

But back to the article. Of course, this is all scientific speculation. Nobody knows what will actually happen.. but the theories put forward in the article are rather intriguing to say the least!


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